22 



CHEMICAL MANUEES. 



According to the French mining statistics of 1887, the approxi- 

 mate extent of the Cote d'Or phosphate deposits is estimated at 5000 

 hectares (12,500 acres), containing 1,500,000 tons of that product. 



5. Cher Pliosjjliate. — Beyond the districts described, a bed with 

 nodules 15 cm. to 20 cm., say 6 to 8 inches thick, situated in the 

 upper Albin, has lately been wrought in the department of Cher. 

 These nodules, of a yellowish-w^hite colour and sometimes loaded 

 with silex, are associated with white quartzose sand and gravels in 

 the proportion of about one- third. They only contain 14 to 16 per 

 cent of phosphoric acid. They are hard, and hence difficult to 

 grind, and their freight was heavy owing to the great distance from 

 a railway station. They were wrought exclusively in the open air, 

 within the radius of Vailly sur Saldre, then after having been 

 washed on the spot, they were ground and dispatched. The irregu- 

 larity of the deposit, the poor phosphoric acid content of the nodules, 

 their great hardness and the heavy cost of freight, rendered these 

 workings expensive, and they were abandoned. 



6. Quercy Phosj)hates {Lot and Neighbouring Departments).— 

 Phosphate deposits occur over a wdde area in Quercy. The phos- 

 phate occurs in concretions in the form of big pockets or vertical 

 veins in the limestone (causses) belonging to the lower oligocene. 

 They are only found in the high limestone plateaus which have 

 been traversed by the fresh waters of the eocene, and almost always 

 in the immediate neighbourhood of tertiary Hots (outliers) left on 

 the spot. These outliers never exceed 350 metres (1148 feet) high, 

 and it would be use'ess to seek for phosphate pockets on Jurassic 

 plateaus of greater altitude. The pockets are very variable ; some 

 have a diameter of 35 metres (115 feet), others are crevasses of 3 

 to 6 metres (10 to 20 feet), foUow^ing a straight line over 90 metres 

 (say 300 feet). All the known pockets end in a point at the bottom, 

 and widen near the surface. The irregular nature of these deposits 

 seems to form an obstacle to their development. Their high phos- 

 phoric acid content seems to have led to a multiplication of badly 

 organized works which ceased to be self-supporting when it was 

 necessary to go lower down. These phosphates are chiefly used in 

 the manufacture of superphosphates to increase the percentage of 

 poor phosphates, so as to bring them to the commercial standard 

 of 15 to 16 per cent of phosphoric acid soluble in ammonium 

 citrate. Their average composition is as follows : — 



TABLE X.— ANALYSIS OF QUERCY PHOSPHATES. 



Per cent. 

 Water and organic matter ..... 5*31 



Phosphoric acid 

 Lime . 

 Carbonic acid 

 Sulphuric acid 

 Fluorine 

 Magnesia 

 Oxide of iron 

 Alumina 

 Insoluble 



35-33 



48-72 



3-42 



008 

 2-24 

 2-78 

 2-12 



100-00 



